Research On High Temperature Oxidation And Mechanical Properties Of A Cast Nickel-base Superalloy

Ni48alloy was made for high temperature material, which was called roll ring in theimported WISCO CSP production line. Due to long work cycle, bearing and transportingbillet continuously in high temperature atmosphere at1150℃for a long time, roll ringalloy suffered from serious high temperature oxidation. As for, Ni48alloy should not onlyhave good high temperature mechanical properties, but also have excellent hightemperature oxidation resistance. Therefore, improving high temperature oxidationresistance of Ni48alloy becomes the key to security application. The research of hightemperature oxidation behavior and mechanical properties of alloy will play an importantrole in predicting the life of the alloy and the working operation condition.In order to better simulate the running status of Ni48alloy at1150℃, enhance thehigh temperature oxidation resistance of alloy, this paper systematically studied theoxidation behavior of Ni48alloy with0.20%mixed rare earth and0.00%mixed rare earthfrom950℃to1150℃for100h. Through the macroscopic oxidation weight and microoxidation film thickness and morphology, the effect of rare earth on high temperatureoxidation resistance is investigated. The results show that the oxidation kinetics curves ofboth Ni48alloy with0.20%of mixed rare earth and0.00%mixed rare earth alloy from950℃to1150℃obey the parabolic law, it can be estimated that the oxidation resistancegrade of both Ni48alloy with0.20%of mixed rare earth and0.00%mixed rare earth iscomplete anti-oxidation within950℃, and anti-oxidation within1050℃and1150℃.Mixed rare earth can appropriately improve the oxidation resistance, reduce the degree ofinternal oxidation and corrosion of Ni48alloy from950℃to1150℃. The oxidationfilms of Ni48alloy from950℃to1150℃are composed of rather dense upper layerconsisted of Mn, Cr and O，compact intermediate layer Cr2O3，as well as loose internallayer SiO2.It is not obvious that adding mixed rare earth to Ni48alloy has effect on high temperature strength at1150℃, high temperature yield strength of Ni48with0.00%mixed rare earth and0.20%mixed rare earth at1150℃is69.6MPa and67.3MPa,respectively. At1150℃, the high temperature oxidation resistance of self-developedNi48alloy is increased more than5%than that of imported alloy, the degree of internaloxidation and corrosion is lower than that of imported alloy, which provides theory basisfor the actual assessment in CSP production line.